Indicating and recording system.



No. 880,273. PATENTED FEB. 25, 1908.

, W. H. BRISTOL.

INDIGATING AND RECORDING SYSTEM.

APPLICATION FILED SBPT.1, 1906.

2 SHEETS-SHEET 1.

Fig-5- PATENTED FEB. 25, 1908.

W. H. BRISTOL.

INDIOATING AND RECORDING SYSTEM.

APPLIOATION FILED SEPT. 1. 1906.

ZSHEBTS-SHEET 2.

' temperatures.

WILLIAM H. BRISTOL, OF NEW YORK, N. Y.

INDICA'IING AND RECORDING SYSTEM.

Specification of Letters Patent.

Patented Feb. 25, 1908.

Application filed. September 1- 1906. Serial 1%. 332.998-

To all whom it may concern:

Be it known that 1, WILLIAM H. BRISTOL, a citizen of the United States, and a resident of New ,York, in the county of New York and State of New York, have invented certain new and useful Improvements in Indicating and Recording Systems, of which the following isa specification.

My invention relates to electrical systems in which electrical apparatus is automatically controlled by the variations of a resistance shunted across said electrical apparatus; and it has for its object a system of this character in which the actual current flowing is extremely small, and in which small variations of a controlling resistance produce considerable effects in the electrical apparatus controlled thereby.

For this purpose my invention consists essentially of a constant source of electro-motive force feeding through a suitable resistance a divided circuitone branch of which contains electrical apparatus automatically controlled by a variable resistance located in the other.

The nature of nay-invention will be best understood in connection with the accompanying drawings, in which Figure 1 is a diagrammatic view of the various electrical connections. Figs. 2 to 4 are views illustrating the application of my invention to the indicating and recording of Fig. 5 is a view illustrating the application of my invention to the recording of a distant water level, showing also a local circuit.

Similar characters of reference designate corresponding parts throughout the several views.

Referring to the drawings, 10 designates an electrical indicating device adapted to indicate small currents, as a milliammeter of the standard type; or, as in Figs. 3 and 5,. a recordin device adapted to record the movements 0 the pointer of such indicating devices. This recording device is preferably of the type disclosed in my prior patent #813,689, of Feb. 27th, 1906, as the movements of the indicating arm are usually extremely delicate having but little motive power actuating them.

11 is a source of electricity of a substantially constant potential of about 1.5 volts.

12 isa resistance, preferably adjustable.

13 and 14 are suitable switches.

15' is a variable resistance such as the resistance box shown in Fi 5 in which the resistance is varied throug the rise and fall of the water in a tank'16'; or as in Figs. 2 to 4, a temperature controlled rheostat as a mercury thermometric rheostat in which the resistance varies with the temperature to which said device is exposed, as the device disclosed in my prior patent #800,792 of Oct. 3rd, 1905,

17, Fig. 5, is a relay controlling a local circuit containing, for example, two lamps 18 and 19 of different color adapted thereby to indicate at a distance from the recording device 10 and the tank 16 whether the level of the liquid in said tank be above or below apredetermined height. Or, thislocal circuit may control other mechanical or electrical devices. 7 4

(a) and (b) are branches of a divided circuit in series with the source of potential 11 and resistance 12the branch (a) containing in series the instrument 10, or instrument 10 and relay 17 as shown in Figs. 3 and 5; and the branch (b) the second or variable resistance 15. The junctions 20 and 21 of these branches are connected to the source of potential 11 by the leads 22 and-23. 24 and 25 are leads to the instrument 10; and 26 and 27 are leads to the variable resistance 15.

In Figs. 2, 4, and 5 I have shown the junctions 20 and 21 located in close proximity to the instrument 10.

' In Fig. 3 I have shown the junction 20 located at one end of .the divided circuit (the instrument end); and the junction 21 at the other, or resistance end. By this arrangement ofthe circuits, an approximate comensation for resistance tern erature errors in the lea"s 25 and 26 is 1provi ed-the resist- 9 ance introduced in eac branch (a) and (1)) through tern erature changes along the leads being t e same. Of course, the resistance changes of the lead 23 due to tem perature variations would affect the accuracy of the reading, but this change in resistance is extremely small as compared to the total resistance of the circuit which is approximately 150 ohms for a potential at t e battery 11 of from one to two volts.

In Fig. 4 I have shown several of the resistance branches (1)), each containing a variable resistance 15 located at different oints, and connected to a common indicatmg instrument 10 through suitable switches 28. By this arrangement I am enabled to indicate upon one and the same instrument, tem eraturesat various locations.

T e operation of my system is as follows reference being had to Fig. 1. The current from battery 11 passes through the resistance 12 to the junction 20 where it divides, part passing through the branch ((1) and the remainder through the branch (1;), uniting at 21, and thence returning to the battery 1 1 through lead 23. The resistance 12 is made comparatively high, say 150 "ohms for a potential of about 1.5 volts at the"battery. An extremely small current thus flows, thereby prolonging the life and maintaining the constancy of the battery 11. The resistance of the branch (a) is fixed; and is low, usually not more than several ohms including the resistance of the instrument 10. The branch (1)) contains the variable resistance 15. which is of several ohms, the resistance depending on the working range etc. The balance of the resistance of said branch dependsupon the leads 26 and 27, which resistance'is a function of the length and cross-section of said leads, but which is kept as low as possible by roviding sufficiently large conductors. T e resistance of the branch (1)) usually ranges from two to five ohms, the greater part of'which is to be includeddn the variable portion 15. This variable resistance is preferably of the mercury thermometric type as the device dis closed in prior patent #800,792 of Oct. 3rd, 1905, andcomprises a mercury thermometer in the shank of which is aresistance wire or filament ada ted to be short-circuited and vice versa y the mercury under the variations of temperature. By providing, this'.thermometric device with a scale suitably graduated, it may further serve to indicate the temperature directly at, that point-the instrument 10 serving to indicate or record this temperature at a point removed from said'device. I prefer to make the resistance 12 adjustable in order to allow of the re-calibration or standardization of the instrument 10. This may readily be accomplished by holding the resistance 15 at a fixed and known temperature, and then adjusting the resistance 12 until the reading upon the instrument 10 corresponds. Or, I ma out out of circuit the entire branch (b) as y means of the switch 14, and adjust the resistance "12 until the instrument 10 reads to a fixed, predetermined point. Any' changp in potential of the battery 11 may thus e detected and corrected for, it being necessary only to adjust the'resistance 12 until the potential at the junction 20 is a predetermined amount-indicated by the.

reading on the-instrumentflO, as explained.

. The difierence of potential between the junctions 20 and j21.must remain constant unless changed by the variations of the variable resistance 15, which variation is thus indicated or recorded by the instrument 10.

Although I have shown the system as specifically applied to the indicating or recording of temperature and temperature variations, it is very evident that it may likewise serve to indicate or record any physical change which will vary directly or can be made to vary the resistance of the branch (b); or to measure resistances themselves, acting as a direct reading ohmmeter.

What I claim as new and desire to secure by United States Letters Patent, is

1. The combination with a source ofelectricity of a substantially constant potential, and a resistance and electrical apparatus in series therewith, of a shunt across said electrical apparatus including means whereby the resistance of the shunt is a preciably varied by physical changes, the W ole being so arranged that the said hysical changes are automatically indicated y said electrical apparatus.

2. In an electrical system: a substantially constant source of electro-motive force; a resistance and electrical .apparatus in series therewith; and a shunt across said electrical apparatus including means whereby the resistance of the shunt is appreciably varied by temperature, the whole being so arranged that the said temperature changes are automatically indicated by said electrical apparatus.

3. In an electrical indicatin system: a substantially constant source OI tive force; a resistance and electrical indicating means in series therewith; and a shunt across said indicating means, including means whereby the resistance of the shunt is appreciably varied by hysical chan es, the whole being so arranged that the sai physical changes are automatically indicated by said indicating means.

system electro-m'osubstantially constant source 0 electro-motive force; an adjustable resistance and electrical indicating means in series therewith; and a shunt across said indicating means including means whereby the resistance of the shunt is appreciably varied by physical changes, the whole being so arranged that the said physical changes are automatically indicated by said indicating means. I

5. In an electrical indicatin system: a substantially constant source 0 electro-motive force; an adjustable resistance and in- [dicating means in series therewith a shunt across said indicating means including means whereby the resistance of said shunt is a preciab y varied by physical -changes, t e whole being so arranged that the said physical changes are indicated by said indicating means; and means to cut in orout of circuit said shunt.

electrical indicating means in series there 6. In an electrical indicatin system; a substantially constant source 0 electro-motive-force; a resistance andan indicating de-- vice in series therewith; a plurality of shunts across said indicatin dev ce, each shunt including means where y the resistance of said shunt is appreciably varied by physical changes, the whole being so arranged that the said physical changes are automatically indicated by said indicating device; and means to individually cut in or out of circuit said shunts. y a

7 .In an electrical indicating system for tern eratures; a substantially-constant source of e ectro-motive force; a resistance and electrical indicating means in seriestherewith; and a shunt across said electrical indicatin means including means wherebythe reslstance of said shunt is appreciably varied by temperature, the whole being so arranged that the said temperature is auto-' matically indicated by said indicating means.

8. In an electrical indicating system for tern eratures a substantially constant source of e ectro-motive force; a resistance and with; a shunt across said indicating means;

and a mercury thermometric resistance changing device located in said shunt.

.9. In an electrical indicating and record-- ing system: a substantially constant source 'of electro-motive force; an adjustable resistance and electrical indicating and recording means in series therewith; and ashunt across said indicating and recording means including means whereby the resistance of the shunt is appreciably variedby physical changes, the'whole being so arranged that the said physical chan es are automatically indicated and recorded iy said indicating and recording means.

resistance and electrical indicatin 11. In an electrical indicating and recording system: a substantially constant source of electro-motive force; an adjustable resistance and indicating and recording means in series therewith; a shunt across said indicating and recording means includin means whereby the resistance of the shunt is ap reciably varied by physical changes, the w ole being so arranged that the said physical changes are automatically indicated and recorded by said indicating and recording means; and means to cut in or out of circuit of said shunt.

12. In an electricalindicating and recording system: a substantially constant source of electro-motive force; a resistance and an indicating andrecording device in series therewith; a plurality of shunts across said indicating and recording device each shunt including means whereby the resistance of the shunt is appreciably varied by physical changes, the w ole being so arranged that the said physical changes are automatically indicated and recorded by said indicating and recording device; and means to individually cut in or out of circuit said shunts.

13. In an electrical indicating and recording system for temperatures: a' substantially constant source 0 electro-motive force; a

and recording means in series therewit and a shunt across said electrical-indicating and recording means whereby the resistance of the-shunt is appreciabl varied by temperatureychanges, the who e being so arranged that the said temperature is automatically indicated and recorded by said indicating and recording means.

14. In an electrical indicating and recording system for temperatures: a substantially constant source of electro-motive force; aresistance and electrical indicating and recording means in series therewith; a shunt across sald indicating and recording means; and a mercu thermometric resistance changing device ocated in said-shunt.

Signed at New York in-the county of New ,York and State of New York this 31st day of August A. D. 1906.

WILLIAM H. BRISTOL.

Witnesses: 1

A. FABER DU FAUR, FREDK. F. SoHUE'rz. 

